For
the most part of human history, people have satisfied their food needs
by hunting and gathering. Although the hunter-gatherers use of fire
may have impacted the environment to a small degree, this is nothing
compared to how subsequent farmers affected their ecological surroundings.
Agriculture inevitably transforms the land, but in what ways it does
so depends upon what type of agriculture, what system or model of agricultural
production is employed.

Farmers
continuously have to make choices about what to plant, how to plant,
when to plant, and what to plant. Together, these decisions will influence
what type of farming system the farmer in question establishes. Decisions
that farmers make will depend on the 'sign of the times', natural, cultural
and economic conditions will inevitably change as time passes by, and
this inherent change will give rise to a continuous evolution of agricultural
systems. Typically, such evolutionary changes involve the intensification
of production systems. Geography very much influences the types of systems
that evolve, and we will look at what types of systems are to be found
in which geographical regions, and do such regional systems share any
distinguishing features.

Agricultural
production systems show a tremendous variation throughout the tropics.
They are hardly ever stable, but are constantly changing. Obviously, the
conscious choices made by farmers on how to fashion their mode of tilling,
sowing, harvesting, etc as well as what inputs to use, influences the
systems that eventually are established. What, then, are the factors influencing
a farmer's choice of a particular system? The
most important factors identified may be categorised into three major
classes: the political/economic frame conditions,
the household characteristics, and the natural
resource base. The figure below depicts the factors influencing
farmers' choice of production systems, and the relationship between farmers'
choices and environmental effects.

Figure
1.
Farmers' choice of production systems

1.
The political/economic
conditions are generally outside the control of farmers, and are determined
by national and regional policies, international markets, and trade regulations.
Conditions of particular importance are prices of inputs and outputs,
markets, infrastructure, and land tenure systems. Farmers' decision making
will also be influenced by the capacity of the extension service, and
access to new technology through research. Political unrest and wars are
events that strongly influence farmers' decision making.The more
farmers are integrated into markets, the more the political /economic
frame conditions are important. Peasants
are typically less integrated into the market than commercial farmers.

2.
The
second major class of factors which influence farmers' decision making
is the household characteristics. Labour and land availability, consumption
needs and food preferences, capital assets, knowledge base (literacy/traditional
knowledge), religion, off-farm income, and willingness to take risk are
all important factors which will influence household decision making.
Poor families with few capital assets (animals, etc.) will in general
be less willing to take risk. Farmers with a good knowledge base can more
easily take part in market activities, and can more effectively make use
of extension services and new technologies.

3.
The
natural resource base is the third major class of factors which influence
farmers' decision making. Some of these natural resources are outside
the control of the farmer, such as climate and water for irrigation, whereas
the farmer can to some extent control soil quality and farm genetic resources.
Farmers need to consider the quality and quantity of these resources when
decisions are made.

The
household production objectives, together with an assessment of the political/economical
frame conditions, the household characteristics, and natural resource
base, will form the basis for households' decision making.
Households differ with regard to production objectives. Poor households
will, in general, be more subsistence-oriented, while better-off households
will be more cash and profit-oriented. The interest to maintain the farm
resources will also differ between households. The key decisions households
make with regard to agricultural production is on what to produce, how
to produce, and how much to produce. Different households make different
decisions due to variation in household characteristics such as labour
availability, access to capital, off-farm income, etc. The sum of decisions
of all households will determine the amount of products offered on the
market, and the relationship between supply and demand of products will,
in a free market, determine the price of products. This is one of the
feedback mechanisms shown in figure 1.

The
decisions farmers make with regard to what to produce and what type of
technology to use will have environmental consequences. The sum of all
farmers' decisions will determine the quality of the future land resources.
The choice of agricultural technology can, for example, determine the
degree of soil erosion, water pollution, and carbon emission. There is
a feedback mechanism between these processes and the quality of the natural
resource base.

Agricultural
production systems will change over time due to changes in the political/economic
conditions, household characteristics, and the natural resource base.
Decision makers
can influence the development of tropical production systems through price
policies, interest rates, land tenure legislation, extension, and research.

Farming
systems have undergone major changes during the course of history.
In pre-agricultural times, people obtained food through gathering,
hunting, and fishing. Such production systems are still existing
in some parts of the tropics.

Figure
2 shows an example of such a gathering system from Mali that is still
existing. In this case, harvesting is done by brushing the ground after
ripe seeds of the Fonio (Panicum laetum) seed have fallen to
the ground. The fonio is not sown, but regenerate each year by natural
regeneration, and hence represents a gathering system, not an agricultural
production system since the seeds are not planted manually. Gathering
systems such as this, although rare, are not a thing of the past although
one might be induced to believe so when reading about current modern
agricultural practices.

As
population density increases, gathering will seldom suffice to feed all,
and rural dwellers would often tend to take up agricultural activities
and establish themselves as farmers. The first type of agriculture introduced
is normally different forms of 'slash and burn' agriculture or fallow
systems. Farmers burn the vegetation and cultivate the land for some years.
The effect of burning is to add plant nutrients, increase soil pH, and
reduce weed infestation. However, yields will decline during the first
years of cultivation due to increased weed infestation and loss of soil
fertility. When the yield becomes too low, the land is returned to fallow
for a period of time before it once again is cleared and burned. This
type of agriculture is found under low population densities and is still
practised in parts of humid and sub-humid areas.

Fallow
systems may subsequently develop into permanent agriculture. There
is generally a strong relationship between farming intensity, population
growth, and agricultural mechanisation.

Fallow
systems dominate when population density is low, whereas annual cultivation
will only appear in more densely populated areas (see table).

Agricultural
intensification implies an increased frequency of cultivation. Other features
of agricultural intensification are transition from hand-hoe to the plough,
an increase in investment for destumping, terracing, use of manure, and
a change from general use rights to specific land rights.

The
following factors have been found to effect the shift from a fallow system
to a more intensive system:

Availability
of new land

Yield level
under shifting cultivation as compared to under permanent agriculture

The cost of
clearing new land

Access to
mechanisation

Access to
markets

Prices (farmers
may revert to shifting cultivation as a response to increase in fertiliser
prices)

The cost of
moving physical structures

The
cost of moving to new land will typically be lower for smallholders and
peasants than for large scale farmers. Large scale/mechanistic farmers
will clear the land completely for roots and stones, whereas small scale
farmers normally do not destump the trees. Clearing the land of roots
and stones will also make it more easy to introduce animal traction for
ploughing. Animal traction is for this reason seldom practised in fallow
systems. Moreover, large-scale farmers may have more easy access
than peasants to purchased inputs useful for maintaining soil productivity.
Fallow systems are therefore more attractive to smallholders and peasants
than to larger-scale farmers.

Major
agroecological
zones of the tropics are arid, semi-arid, sub-humid, humid and highland
areas. There is, in general, a strong relationship between agro-climatic
conditions, population density, cropping systems, and livestock production
(please see table 2). Animal
grazing systems will also differ between arid, semi-arid, humid and
highland areas.

Arid Areas

Arid
areas are characterised by low population density, and nomadic
livestock systems are often practised A nomad is highly mobile, but
does not necessarily return to the same base every year. This high level
of mobility is needed, as there is a tremendous variability in rainfall
across space and time. A nomad does not usually grow crops, as arid areas
are often too dry for rainfed agriculture. However, agriculture and gardening
may be practised in the proximity of an oasis.

Semi-Arid Areas

The
semiarid tropics is characterised by permanent agriculture, and livestock
production is often a mix of transhumance
and sedentary
livestock production. The natural vegetation is various forms of savannahs.
Agropastoralism is common under semiarid conditions. Agropastoralism comprises
a range of adaptations from some minor annual planting of a cereal combined
with a predominantly pastoral way of life, to a closely integrated system
of crops and livestock on a permanently settled farm (mixed farming). Mixed
cropping is important in semiarid tropics, sub-humid and highland
areas. Cereal crops like pearl millet and sorghum
are important crops. Cereals
are ubiquitous crops in semiarid, subhumid and highland areas, because
they can be easily stored and traded. Cereal systems, therefore, allow
wealth accumulation and is for this reason one of the fundaments for old
civilisations. Other important crops in semiarid tropics are grain legumes
like e.g. cowpea and groundnut.
Cereals combined with grain legumes constitute a diet of very good quality.

Soils
in semiarid tropics are often poor in nitrogen and phosphorous. Farming
in semiarid areas is characterised by relatively low response to inputs,
high erosion rates, and erratic rainfall which often causes extreme variation
in yield. In the Sahel, the livestock herders bring their animals to fields
belonging to farmers after harvest. The animals feed on the crop residues
and leave manure for the benefit of further crop production. The parasitic
weed striga often causes problems in semiarid regions and problems
are more severe in areas with low soil fertility. It is a very difficult
weed to control because the seeds can remain dormant for many years in
the soil, and because it attacks the most important crop species in the
semiarid tropics. In addition, it a has a high ability to adapt to new
resistant varieties. Various measures for controlling striga has been
developed. Various types of traditional agroforestry systems is often
practised in semiarid areas. One of these systems is pearl millet and
the tree Acacia albida, which sheds its leaves in the dry season
and fixes nitrogen, and thus is well adapted to the climatic conditions.

Sub-humid Areas

Sub-humid
areas probably have
the best conditions
for agriculture, and population density is for this reason high. More
plant species are grown in these areas, and cropping systems are often
more complex. Maize and
rice are
major crops in sub-humid areas. Tuber crops like cassava and sweet potatoes
are more frequently found in this region as well, as compared to the more
arid zones. Different crops are often combined on the same piece of land
in mixed cropping
systems, which are often associated with subsistence production. Intensification
of mixed cropping is difficult due to problems with mechanising the production,
and applying the correct amount of inputs. Crop rotation systems can provide
many of the same benefits as mixed cropping systems. Livestock production
is mainly sedentary in sub-humid areas.

Humid Tropics

The
natural vegetation in humid tropical areas is in most cases lush rainforest.
Most of the plant nutrients are absorbed in the vegetation, and not in
the soil. Soils in the humid tropics are often leached, resulting in acid
soils with problems of aluminium toxicity. Major crops in the humid tropics
are maize, tuber crops
, rice ,
plantains,
and tree crops such as oil palm. Local peoples in such areas have developed
three different production systems that, in the traditional form, have
proved to be sustainable: (1) Shifting cultivation, (2) Permanent home
gardens, and (3) Lowland rice production on submerged soil.

1.
In shifting
cultivation, the vegetation is cleared by felling of trees, burning,
and planting of crops for a short period, most often only for one year.
After harvesting the planted crops, the land is left for natural regeneration
and quickly forms secondary forest (see above).

2.
The permanent
home gardens are structured as multistorey cropping systems. They
replace natural forests with unsubsidised nutrient cycling and may function
well if most of harvested production is for subsistence and when the waste
is returned to the cropped land. In home garden multistorey systems this
is frequently the case. The home garden receives all household waste and
may also serve as field latrine or site for shifting latrines. In this
way, nutrients are returned to the land from which they are taken.

3.
There exist several
forms of lowland rice production. Traditional
wet-rice cultivation exploits natural flooding during summer rains (monsoon
climate). Local varieties are normally sensitive to the day length (photoperiod).
In that way growth, flowering and seed maturation is timed according to
the season of normal flooding. That system is classified as “rainfed lowland”.
We also have deep water or flood-prone rice systems; from a half to several
metres of inundation (also season dependent). That cultivation system
is found in river basins mainly in South and Southeast Asia, but also
along the Niger River in West Africa. The modern intensive form of rice
cultivation is called “irrigated rice” and assumes a water management
that can assure optimal flooding (about 5 cm) throughout the growing season(s),
often long enough to allow double cropping. With year-round continuous
submersion more than two crops is possible. In the Mekong Delta in Vietnam,
some farmers manage 7 crops of rice in a two-year period. Such cultivation
requires day length-neutral (non-photoperiodic) varieties to allow normal
crop development independent of the season. Hybrid
rice has been developed. Yields are higher, but it requires farmers
to change seeds every year.

Livestock
density is low in humid areas due to prevalence of livestock pests, particularly
in Africa. Trypanosomiasis, which is transmitted by the tsetse fly, is
a major threat to livestock in the forest fallow and bush fallow systems.
The reason is that the tsetse fly is shade-loving, and can only survive
under forest bush cover. Pest and diseases often cause serious losses
in humid areas. Storage of agricultural products is another serious problem
in the humid tropics.

Highland Areas

Most
highland areas have a high population density. Important crops are wheat,
maize and barley in addition to grain legumes. Coffee and tea are important
cash crops in humid highland areas. More livestock
is found in the highlands and mixed cropping is practices, and animal
traction is more widely used.

This
lecture shows that there is a tremendous variation in the type of agricultural
production system practised in the tropics. It has been shown that farmers
make their decision based on political /economic frame conditions, household
characteristics, and the natural resource base. These factors, together
with household production objectives, form the basis for household decision
making. Households decide on what to produce, how to produce, and how
much to produce. These choices will have environmental consequences, and
will determine the quantities and quality of the products offered on the
market.

Questions
for Reflection

What are the major factors that determine farmers' choices of
production systems?

What are the features of agricultural intensification?

Why is it difficult to introduce improved agricultural practices
in areas with low R-values?

What are the major differences between farming systems in semiarid,
humid and highland areas?

Further
Reading

McCalla, Alex F. 'Agriculture and Food Needs to 2025'

The article is taken from
the book 'International Agricultural Development' (1998) edited by Carl
K. Eicher and John M. Staatz, Johns Hopkins University.Press.

Assignment
1

a) Which of the scenarios
that was described in the Foreword (see the folder named Course Description) most closely reflect your own feelings?
Please provide
your reasons for choosing that particular scenario. You may refer
to the article by Alex F. McCalla 'Agriculture and Food Needs
to 2025'. Post your answer in the Discussion Forum, under the
heading 'Your name Ass1a'.

b)
Choose a geographical region in your home country, or a country
that interests you specifically, and describe the agricultural
production systems to be found in this region. Discuss what factors
have been most important in shaping the evolution of this particular
production system. Post
your answer in the Discussion Forum, under the heading 'Your name Ass1b'.